Wednesday, May 7, 2014

The Principle Of Resistance Temperature Device

By Tracie Knight


Temperature is measured using different methods depending on the environment. RTD or Resistance temperature device is based on the scientific fact that changing the temperature of a conductor will affect its resistance. The flow of electric current as a result of heating or cooling is used in calibrating the devices. The principle of correlation is used with a great deal of standardization.

Platinum is a common metal because it displays a constant reaction over a wider range of change in heat. This gives an incredible accuracy level which is important for industrial processes. Temperature sensitivity is likely to affect the results of a production process.

Industrial processes are very specific when dealing with heat. This raises the need for high sensitivity and faster response. The metals used in this case are carefully selected to ensure that their response time is minimized. It gives a signal to control and monitoring units to take action before the outcome is compromised.

The industries that benefit from this technology include manufacturers of appliances, automotive industry, control sections and HVAC. Production plants with measuring and testing units need to constantly monitor the temperatures. A higher level of consistency and accuracy is required to achieve desired results. Common metals for this purpose include copper, nickel and platinum.

The properties that make an element favorable for this purpose include the heat range and how it responds to fluctuations. Processes such as extraction are sensitive to changes in temperature. Any distortion due to heating or cooling is likely to damage such appliances and compromise their operations.

Exposure to heat causes varying reactions which is considered a limitation when using RTDs. Temperatures beyond 660 degrees Celsius have been known to damage the conductor or cause it to misbehave. Too much heat causes impurities to contaminate the conductor. They come from the sheath and affect measurement given.

Impurities found at boundaries and changing temperatures have a significant effect on the behavior of conductors in RTDs. This has been clearly noted when it is below 270 degrees or 3 Kelvin. The elements used have very few phonons which explains their behavior. This affects their sensitivity to slight changes in temperature.

The challenges posed by the use of RTDs include accuracy when converting the readings. The relationship between resistance and temperature is a delicate one and easily affected by other conditions. Sensitivity changes depending on heat. This is likely to give erroneous results.

Prolonged thermal exposure is likely to affect the properties of conductors used. There is a possibility of recording different measurements over a cycle of heat and cold. This behavior is referred to as hysteresis. It has been observed in different elements and threatens the use of RTDs in sensitive and long running industrial processes.

Interference from the sheath and impurities on the device cause loss of heat. This affects the accuracy of such devices. There is a possibility of current flowing through the conductor from other sources. Other factors that affect accuracy include the number of wires used as conductors. The response time for these devices is not satisfactory in some instances.




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